Lance holder with multiple-tolerance clamping head

ABSTRACT

A lance holder  1  characterized by a high level of operating safety is equipped with a holder or tube fixing system which reliably prevents even a bent lance tube  2  from turning in the lance holder  1 . The clamping head  3  has a fixing part  4  and a clamping part  5  which ensure punctiform fixing by means of suitably-displaceable pressure elements  16  in the form of balls  20 . Three such balls  20, 20′  are distributed around the circumference and provide for secure fixing and a wide tolerance range in respect of the dimensions of the lance tubes  2 . Said wide tolerance range is also ensured by the possibility of using sealing sleeves  6  with a large internal diameter, which are pressed securely and directly against the wall  18  of the lance tube  2  without compression by insertion of a wedge  22.

The invention concerns a lance holder for lance tubes used in the iron and steel industry having a clamping head which has a fixing part and a clamping part, to which a sealing sleeve clamping and thus sealing the lance tube introduced is allocated.

Lance holders with a clamping head and a slag non-return safety device or backburn safety device serve to hold the lance tube required for oxidation securely and an the other hand to prevent slag from running back to the oxygen inlet when the blasting process is completed or interrupted. According to DE 23 27 595C, a gas-permeable sintered metal disc, which prevents slag return, is arranged shortly before the oxygen hose. This mechanical barrier to slag return does not always fulfil requirements, particularly if high volumes of oxygen have to flow through, because then a sintered metal disc naturally leads to difficulties. The upstream valve arrangement also performs a sort of slag-return prevention function, closing when the gasket arranged above has been burned due to returning slag. The lance tube inserted into the lance holder is held by a clamping head with a collet arranged therein. The effect of the teeth of the collet holds the lance tube inserted in the lance holder. A sealing sleeve is arranged behind this collet and is affected by the inserted tube and deformed so that it is in close contact with the outside of the lance tube. This close contact due to deformation of the sealing sleeve has the initial disadvantage that the sealing sleeve may stick to the lance tube, so that the remainder of the lance tube can only be removed with difficulty or by removing the sealing sleeve as well when the collet is opened. This problem and the particular configuration of the collet have the disadvantage that the diameter of the respective lance holder must be quite precisely matched to the diameter of the lance tubes to be inserted and held. Currently, lance holders are in use which can accept and fix imperial tubes and others which can accept metric lance tubes.

Only very narrow tolerances are possible due to the movement of the collet and ultimately also the sealing sleeve, usually in the range of 0.2 mm. As these lance tubes are consumables, businesses are ultimately forced to purchase them with both imperial and metric tube diameters, causing problems for staff, because they are usually depend on lance holders which accept only a few tube diameters. This means that damage and accidents occur repeatedly, because the lance holder components which are crucial to fixing and sealing are damaged during operation with a diameter of tube which is too great or too small, rendering the lance holder unusable. As these lance tubes introduce oxygen into the melt and usually have to be curved for this purpose, the molten steel can endanger operators, particularly if the lance tubes slip out or if other problems occur. Even if the operators are protected by protective clothing and hard hats, protection against molten steel is inadequate, so that injuries and detrimental effects can occur repeatedly.

The invention is based upon the problem of creating a lance holder for multiple and simultaneously as many dimensions as possible, and which is safe to operate and easy to handle.

The problem is solved according to the invention by the fixing part comprising the inserted lance tube is provided with a leading bevel in which pressure elements distributed around the circumference are guided which are displaceable at right angles to the longitudinal axis of the lance tube and by means of which fixing part a clamping part having a pressure bevel corresponding to the leading bevel is arranged and formed in an influenceable manner.

By means of a lance holder designed in such way it is first of all possible to hold the inserted lance tube precisely and securely, because it is held precisely by the pressure elements, when operating the clamping head or particularly the clamping part which is pushed onto the fixing part. The sealing sleeve is relieved simultaneously. This ensures that once the lance tube is inserted, it can only be removed by deliberate operation of the clamping part. However, the lance tube is securely held throughout operation, the sealing sleeve being protected against sticking by further measures described below and itself having a diameter which allows the use of lance tubes of different diameters. The range of acceptance of different lance tube diameters is restricted by the leading bevel and the correspondingly-designed clamping part, but a considerable reduction in the sizes of the lance holder is possible. The tolerance range is increased to approximately 0.5-3.00 mm by the design according to the invention, depending upon the structure of the lance holder. The number of lance tubes currently in use, for which a variety of lance holders, tailor-made to the respective dimensions were necessary, can thus be reduced to 6-7. This is rendered possible because the displaceable pressure elements act and take effect as soon as lance tubes of the sizes intended for the respective lance holder are inserted, whilst fixing a lance tube with a smaller external circumference still remains possible, because the displaceable pressure elements then only take effect after a corresponding displacement path and fix the lance tube.

A purposeful embodiment of the invention provides for the pressure elements all being formed and arranged to be displaced simultaneously and uniformly by the pressure bevel against the wall of the lance tube. Insertion of the respective lance tube does not cause tilting or other problems with the smallest possible lance tube diameters, because the individual pressure elements are stressed and pressed against the wall of the lance tube evenly and simultaneously.

A further purposeful embodiment provides for the pressure elements being formed so as to generate punctiform and/or linear load pressure on the wall. Pressure elements are thus used which do not exercise pressure across the surface of the lance tube, but punctiform or linearly, so that a higher, more targeted pressure or load pressure may be generated.

A particularly purposeful embodiment provides for the pressure elements being formed as balls, so that the aforementioned punctiform load pressure can be generated in such a way that the lance tubes are held optimally, the lance tubes usually consisting of mild steel, e.g. St 37, whilst the balls are made of a hardened material, thus being capable of a long useful life.

Particularly even and secure fixing of the lance tubes in the lance holder is provided if three balls are evenly distributed around the circumference in the leading bevel of the fixing part, as pressure elements. Bores are then purposefully present in the leading bevel, through which the respective ball may be pressed onto the surface of the lance tube by the clamping part pushed on or displaced and its pressure bevel. For this purpose, the clamping part has, as aforementioned, a matched pressure bevel which extends uniformly, ensuring that all three balls are moved towards the inserted lance tube in their bores simultaneously, to hold it securely and thus fix it permanently.

Lengthwise deformation of the sealing sleeve, i.e. compression, is waived, to prevent it from sticking when it contacts the inserted lance tube. Deformation would have to involve the application of considerable force, particularly for lance tubes with greater tolerances. This is avoided by the solution according to the invention, in accordance with which the fixing part has a wedge on the side opposite the leading bevel, insertable between the external wall of the sealing sleeve and the surrounding protective casing. Said wedge acts on the sealing sleeve and ensures that the latter is in sufficiently close contact with the external wall of the lance tube, ensuring a secure seal, advantageously without compression in the longitudinal direction being necessary. For this purpose, the wedge is displaced longitudinally, pressing the sealing sleeve against the wall of the lance tube, as desired. If the fixing part and its wedge are withdrawn when released, the sealing sleeve will be relieved, can regain its shape and separate from the rest of the lance tube, so that the lance tube can be removed from the lance holder easily. Such even pressure on the lance tube has the additional advantage that consistently superficial contact is possible, which would not be guaranteed if the sealing sleeve were compressed.

Displacement of the clamping part on to the fixing part purposefully takes place by the clamping part of the clamping head having a clamping sleeve which encloses the clamping part and is formed on an external thread of the protective casing such that it can be displaced. It may thus be ensured that the clamping part can be correspondingly pushed onto the fixing part and the balls thus pressed against the wall of the lance tube with little force. This process takes place simply by turning the clamping sleeve, which may be further facilitated by roughened contact surfaces and the like.

Ease of movement of this displacement process is specifically enhanced by arranging a ball bearing between the front wall of the clamping part and the clamping wall of the clamping sleeve. Said ball bearing between the clamping sleeve and clamping part reduces the friction which occurs in the clamping process so that it may take place without the application of great force.

The lance tube must be inserted far enough into the lance holder, i.e. through the sealing sleeve. To ensure this, provision is made for a check valve to be arranged between the sealing sleeve and a backburn safety device, with a stop which perceptibly restricts potential insertion. The lance tube inserted as far as the stop then releases the gas flow when clamped. Operation therefore cannot commence when the lance tube has been inserted in the lance holder until it has been inserted far enough to achieve precise sealing by the sealing sleeve. The check valve is opened simultaneously. The check valve is then held open by the lance tube until the lance tube is or has to be removed, when a spring then moves the valve back into its closed position automatically.

Further provision is made for a non-return valve, to be opened by the gas flow, to be provided on the opposite side of the backburn safety device, to render the entire lance holder safe. This ensures that the gas flow can enter the lance holder at the requisite pressure and is cut off again automatically if the pressure falls too far. Precise, safe operation of the lance holder is thus guaranteed.

In order to make it possible to install and maintain the parts downstream of the lance holder itself separately, the invention also provides for the backburn safety device with the valves to be allocated to a safety casing removably connected to the protective casing. Both casings are preferably bolted together.

It has already been stated above that the number of sizes required can be reduced considerably by the lance holder according to the invention. According to the invention provision is made for the fixing part, clamping part and sealing sleeve to be formed having tube tolerances of 3-4 mm for group dimensions admitting both metric and imperial tubes. This makes it possible, as already mentioned above, to cope with about seven holder sizes, whilst currently far more than 15 such holder sizes have to be considered in order to make fairly reliable lance holder operation possible. Reliable operation is always guaranteed by the new lance tube fixing system.

The invention is particularly distinguished by the creation of a lance holder which can be used in both the iron and steel industries without an unnecessary potential hazard to the operators by mishandling or operation of the lance holder, or due to inadmissible lance tube diameters. Firstly, the lance tube inserted in the lance holder is optimally fixed therein, simultaneously ensuring that the lance tube is always inserted far enough into the lance holder in operation, i.e. as far as the stop. When the stop is reached, or shortly before, during clamping, the check valve blocking the inflow of gas is opened and the gas can flow through the lance holder into the lance tube previously held in the sealed lance tube. The necessary sealing of the lance tube no longer takes place by means of a sealing sleeve deformed longitudinally, but by the sealing sleeve being pressed evenly and securely against the respective lance tube by a wedge. This creates the possibility of using sealing sleeves with a larger diameter than the external diameter of the lance tube. The purposeful design of the clamping head with pressure elements in the form of balls displaceable at right angles to the longitudinal axis primarily ensures punctiform application of the load pressure and thus optimal fixing of the lance tubes inside the lance holder. This ensures that the lance tube cannot rotate in the lance holder, the lance holder being fixed by the clamping head and the sealing sleeve, but so securely by the clamping head that any detrimental effect whatsoever on the fixing of the lance tube is precluded. Secure retention is also provided for deformed lance tubes, because sufficient force can always be applied by the punctiform or linear fixing of the lance tubes in the lance holder. Suitable marking can visibly and easily establish the tube diameters for which the respective lance holder is intended for the operators. This precludes any hazards whatsoever.

Further details and advantages of the subject of the invention emerge from the following description of the relevant drawing, which shows a preferred specimen embodiment with the necessary details and individual components.

FIG. 1 is a side view of a lance holder with a moulded rotary valve;

FIG. 2 is a cross-section of the lance holder with a 13.2 mm diameter tube clamped in;

FIG. 3 is a perspective representation of the lance holder shown in FIG. 2;

FIG. 4 is a cross-section of a lance holder with a tube with a circumference of 17.5 mm clamped in, and:

FIG. 5 is a cross-section of a lance holder in its relaxed state, without a lance tube.

FIG. 1 is a side view of a lance holder 1. A lance tube 2 is inserted in the clamping sleeve 25 from the front. The clamping sleeve 25 and the clamping head 3 contain a fixing part 4 and a clamping part 5 not shown here, which cooperate with the sealing sleeve 6 and are accommodated in the clamping head 3 formed as a protective casing 9. The adjacent safety casing 10 accommodates the requisite valves which will be considered below. A rotary valve 11 is screwed onto this safety casing 10, which bears the manufacturer's name 40.

A cross-section through the lance holder 1 shown in FIG. 1 is shown in FIG. 2, where it may be seen that the lance tube 2 is inserted far into the lance holder 1 through the clamping head 3. The aforementioned sealing sleeve 6 is pressed against the wall 18 of the lance tube 2 by a wedge 22 so that full sealing is achieved. Said wedge 22 forms the end 21 of the fixing part 4 opposite the leading bevel 14. When the clamping head 3 or the clamping sleeve 25 is operated, the wedge 22 is pushed in between the outer wall 23 of the sealing sleeve 6 and the protective casing 9 so that the sealing sleeve 6 is deformed and is in close contact with the wall 18.

Whilst the opposite end 21 of the fixing part 4 causes the deformation and presses the sealing sleeve 6 against the wall 18, the front end has a leading bevel 14, in which pressure elements 16 are arranged which may be displaced at right angles to the longitudinal axis 15 of the lance tube 2. Said pressure elements 16 are affected by the pressure bevel 17 of the clamping part 5, which is pushed onto the correspondingly formed leading bevel 14 when the clamping sleeve 25 or the clamping head 3 is turned. The pressure elements 16 are formed as balls 20, as shown in FIG. 2 and FIG. 3, the balls 20 being pressed directly against the wall 18, so that secure fixing of the lance tube is guaranteed. Three such balls 20, 20′ are distributed around the circumference, all of which are affected uniformly and simultaneously by the pressure bevel 17. In order to make this movement sequence, i.e. the displacement of the clamping part 5 by the clamping sleeve 25 as uniformly as possible, the balls of a ball bearing 30 are arranged between the front wall 28 of the clamping part 5 and the clamping wall 29 of the clamping sleeve 25 or clamping head 3. This minimises friction so that the necessary forces can be applied without problems by the external thread 27 on the protective casing 9 and the internal thread 26 of the clamping sleeve 25, to ensure uniform, simultaneous displacement of the pressure bevel 17 onto the pressure elements 16 or the balls 20.

When the lance tube 2 is inserted in the lance holder 1, the check valve 32 arranged between the sealing sleeve 6 and the backburn safety device 7 is opened. At this point, the outside wall 8 or 23 of the sealing sleeve 6 has not yet been stressed by the wedge 22, so the lance tube 2 can easily be inserted correspondingly far. When the stop 33 is reached, the check valve 32 is, as described, displaced against the force of a spring so far that gas can now be fed into the lance holder 1, although the fixing measures have to be taken first. Only then can the gas flow 34 be released, which opens the non-return valve 36 arranged on the side 35 opposite the backburn safety device 7. For this purpose, a release and check valve not shown here must first be operated.

FIG. 3 shows the lance holder 1 with the lance tube 2 of the smallest diameter in the working position, i.e. non-return valve 36 can now be opened by the gas flow 34, to allow the gas to flow through. The illustration in FIG. 3 emphasizes that the pressure elements 16 used in the form of balls 20 are advantageously suitable for exercising punctiform pressure on the lance tube 2 and fixing it securely.

FIG. 4 shows a lance holder 1 with a lance tube 2 of the largest possible diameter, 17.5 mm, intended for this type of lance holder inserted. In comparison with FIG. 2 it will be clear that the particular shape of the sealing sleeve 6 ensures that secure sealing still takes place at this considerably larger diameter. The wedge 22 is pushed up far enough to achieve this, wherein the balls 20 can already exercise their fixing effect, although the pressure bevel 17 is only having a small effect on them. In contrast, it may be recognised from the illustration in FIG. 2 that the balls 20 have only reached the secure position on the wall 18 by correspondingly far displacement of the pressure bevel 17 of the clamping part 5.

The non-return valve 36 can also now be opened in the position shown in FIG. 4 by opening the gas path, to allow the gas flow 34 to pass through the lance holder 1 and enter the lance tube 2.

Finally, FIG. 5 is a cross-section of a lance holder 1 in its relaxed state, because no lance holder 2 has yet been inserted.

The check valve 32 is moved into its closed position by the allocated spring and the stop 33, which is affected by the lance tube 2 to be inserted, is pushed back correspondingly far here. The lance tube 2 is inserted into the insertion channel 37 as far as this stop 33 and the entire component then displaced so that the check valve 32 opens.

It may be seen from FIG. 5 that the balls 20 are borne in bores 38 so that they may be displaced at right angles to the longitudinal axis 15 of the lance tube 2. This particular embodiment makes precise fixation of the inserted lance tube 2 possible, including when lance tubes with the diameters shown in FIG. 4 or FIG. 2 are to be introduced. Appropriately formed lance holders must be used for other diameters, the advantage of the lance holder according to the invention predominantly being regarded as being that tube tolerances of 3-4 mm can be handled safely, as aforementioned. It is also advantageous that the oxygen or gas can only flow if the lance tube 2 is pushed into lance holder 1 as far as the stop 33. The lance holder 1 has a considerably reduced overall weight and a very compact design. The clamping head 3 is hardened and can have a long useful life. It is also advantageous that the lance holder 1 can be assembled and dismantled easily, making it particularly well suited to work in the iron and steel industries. 

1. A lance holder for lance tubes (2) used in the iron and steel industry with a clamping head (3), which has a fixing part (4) and a clamping part (5) and to which a sealing sleeve (6) interlocking the inserted lance tube (2) and thus sealing it is allocated, wherein the fixing part (4) comprising the inserted lance tube (2) is provided with a leading bevel (14), in which pressure elements (16) distributed around the circumference are guided which can be displaced at right angles to the longitudinal axis (15) of the lance tube (2) and by means of which fixing part a clamping part having a pressure bevel corresponding to the leading bevel is arranged and formed in an influenceable manner.
 2. The lance holder according to claim 1, wherein the pressure elements (16) are all formed and arranged to be displaced simultaneously and uniformly by the pressure bevel (17) against the wall (18) of the lance tube (2).
 3. The lance holder according to claim 2, in that wherein the pressure elements (16) are formed so as to generate a punctiform and/or linear pressure load on the wall (18).
 4. The lance holder according to claim 1, wherein the pressure elements (16) are formed as balls (20).
 5. The lance holder according to claim 1, wherein three balls (20, 20′) acting as pressure elements (16) are arranged in the leading bevel (14) of the fixing part (4), evenly distributed around the circumference.
 6. The lance holder according to claim 1, wherein the fixing part (4) on the side (21) opposite the leading bevel (14) has a wedge (22) insertable between the outer wall (23) of the sealing sleeve (6) and the surrounding protective casing (9).
 7. The lance holder according to claim 1, wherein the clamping part (5) of the clamping head (3) has a clamping sleeve (25) which is formed so as to enclose the clamping part (5) and to be displaceable on an external thread (27) of the protective casing (9).
 8. The lance holder according to claim 7, wherein a ball bearing (30) is arranged between the front wall (28) of the clamping part (5) and the clamping wall (29) of the clamping sleeve (25).
 9. The lance holder according to claim 1, wherein a check valve (32) is arranged between the sealing sleeve (6) and a backburn safety device (7), which is affected by the lance tube (2) inserted as far as the stop (33) and which is formed so as to release the gas flow (34) when open.
 10. The lance holder according to claim 1, wherein a non-return valve (36), to be opened by the gas flow (34), is provided on the opposite side (35) of the backburn safety device (7).
 11. The lance holder according to claim 1, wherein the backburn safety device (7) with the valves (32, 36) is allocated to a safety casing (9) removably connected to the protective casing (10).
 12. The lance holder according to claim 1, wherein the fixing part (4), clamping part (5) and sealing sleeve (6) are formed with tube tolerances of 3-4 mm for group dimensions admitting both metric and imperial tubes. 